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49
Hash Functions Based on Block Ciphers
 Proc. of EUROCRYPT 92
, 1993
"... . Iterated hash functions based on block ciphers are treated. Five attacks on an iterated hash function and on its round function are formulated. The wisdom of strengthening such hash functions by constraining the last block of the message to be hashed is stressed. Schemes for constructing mbit ..."
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Cited by 54 (7 self)
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. Iterated hash functions based on block ciphers are treated. Five attacks on an iterated hash function and on its round function are formulated. The wisdom of strengthening such hash functions by constraining the last block of the message to be hashed is stressed. Schemes for constructing mbit and 2mbit hash round functions from mbit block ciphers are studied. A principle is formalized for evaluating the strength of hash round functions, viz., that applying computationally simple #in both directions# invertible transformations to the input and output of a hash round function yields a new hash round function with the same security. By applying this principle, four attacks on three previously proposed 2mbit hash round functions are formulated. Finally, three new hash round functions based on an mbit block cipher with a 2mbit key are proposed. 1 Introduction This paper is intended to provide a rather rounded treatment of hash functions that are obtained by iterati...
On the impossibility of highlyefficient blockcipherbased hash functions
 in Advances in Cryptology—EUROCRYPT 2005
, 2005
"... Abstract. Fix a small, nonempty set of blockcipher keys K. We say a blockcipherbased hash function is highlyefficient if it makes exactly one blockcipher call for each message block hashed, and all blockcipher calls use a key from K. Although a few highlyefficient constructions have been propose ..."
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Cited by 27 (3 self)
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Abstract. Fix a small, nonempty set of blockcipher keys K. We say a blockcipherbased hash function is highlyefficient if it makes exactly one blockcipher call for each message block hashed, and all blockcipher calls use a key from K. Although a few highlyefficient constructions have been proposed, no one has been able to prove their security. In this paper we prove, in the idealcipher model, that it is impossible to construct a highlyefficient iterated blockcipherbased hash function that is provably secure. Our result implies, in particular, that the Tweakable Chain Hash (TCH) construction suggested by Liskov, Rivest, and Wagner [7] is not correct under an instantiation suggested for this construction, nor can TCH be correctly instantiated by any other efficient means.
Formalizing human ignorance: Collisionresistant hashing without the keys
 In Proc. Vietcrypt ’06
, 2006
"... Abstract. There is a foundational problem involving collisionresistant hashfunctions: common constructions are keyless, but formal definitions are keyed. The discrepancy stems from the fact that a function H: {0, 1} ∗ → {0, 1} n always admits an efficient collisionfinding algorithm, it’s just t ..."
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Cited by 22 (0 self)
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Abstract. There is a foundational problem involving collisionresistant hashfunctions: common constructions are keyless, but formal definitions are keyed. The discrepancy stems from the fact that a function H: {0, 1} ∗ → {0, 1} n always admits an efficient collisionfinding algorithm, it’s just that us human beings might be unable to write the program down. We explain a simple way to sidestep this difficulty that avoids having to key our hash functions. The idea is to state theorems in a way that prescribes an explicitlygiven reduction, normally a blackbox one. We illustrate this approach using wellknown examples involving digital signatures, pseudorandom functions, and the MerkleDamg˚ard construction. Key words. Collisionfree hash function, Collisionintractable hash function, Collisionresistant hash function, Cryptographic hash function, Provable security. 1
Seven Cardinal Properties of Sensor Network Broadcast Authentication
 SASN'06
, 2006
"... We investigate the design space of sensor network broadcast authentication. We show that prior approaches can be organized based on a taxonomy of seven fundamental proprieties, such that each approach can satisfy at most six of the seven proprieties. An empirical study of the design space reveals po ..."
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Cited by 21 (4 self)
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We investigate the design space of sensor network broadcast authentication. We show that prior approaches can be organized based on a taxonomy of seven fundamental proprieties, such that each approach can satisfy at most six of the seven proprieties. An empirical study of the design space reveals possibilities of new approaches, which we present in the following two new authentication protocols: RPT and LEA. Based on this taxonomy, we offer guidance in selecting the most appropriate protocol based on an application’s desired proprieties. Finally, we pose the open challenge for the research community to devise a protocol simultaneously providing all seven properties.
Constructing cryptographic hash functions from fixedkey blockciphers. Full version of this paper
, 2008
"... Abstract. We propose a family of compression functions built from fixedkey blockciphers and investigate their collision and preimage security in the idealcipher model. The constructions have security approaching and in many cases equaling the security upper bounds found in previous work of the aut ..."
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Cited by 19 (5 self)
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Abstract. We propose a family of compression functions built from fixedkey blockciphers and investigate their collision and preimage security in the idealcipher model. The constructions have security approaching and in many cases equaling the security upper bounds found in previous work of the authors [24]. In particular, we describe a 2nbit to nbit compression function using three nbit permutation calls that has collision security N 0.5,whereN =2 n, and we describe 3nbit to 2nbit compression functions using five and six permutation calls and having collision security of at least N 0.55 and N 0.63. Key words: blockcipherbased hashing, collisionresistant hashing, compression functions, cryptographic hash functions, idealcipher model. 1
Building PRFs from PRPs
 Advances in Cryptology—CRYPTO ’98, LNCS 1462
, 1998
"... . We evaluate constructions for building pseudorandom functions (PRFs) from pseudorandom permutations (PRPs). We present two constructions: a slower construction which preserves the security of the PRP and a faster construction which has less security. One application of our construction is to ..."
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Cited by 18 (0 self)
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. We evaluate constructions for building pseudorandom functions (PRFs) from pseudorandom permutations (PRPs). We present two constructions: a slower construction which preserves the security of the PRP and a faster construction which has less security. One application of our construction is to build a wider block cipher given a block cipher as a building tool. We do not require any additional constructionse.g. pseudorandom generatorsto create the wider block cipher. The security of the resulting cipher will be as strong as the original block cipher. Keywords. pseudorandom permutations, pseudorandom functions, concrete security, block ciphers, cipher feedback mode. 1 Introduction and Background In this paper we examine building psuedorandom functions from pseudorandom permutations. There are several well known constructions for building pseudorandom permutations from pseudorandom functions, notably [LR88]. However, the only results we are aware of for going in t...
Building a collisionresistant compression function from noncompressing primitives
 In ICALP 2008, Part II
, 2008
"... Abstract. We consider how to build an efficient compression function from a small number of random, noncompressing primitives. Our main goal is to achieve a level of collision resistance as close as possible to the optimal birthday bound. We present a 2nton bit compression function based on three ..."
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Cited by 16 (3 self)
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Abstract. We consider how to build an efficient compression function from a small number of random, noncompressing primitives. Our main goal is to achieve a level of collision resistance as close as possible to the optimal birthday bound. We present a 2nton bit compression function based on three independent nton bit random functions, each called only once. We show that if the three random functions are treated as black boxes then finding collisions requires Θ(2 n/2 /n c) queries for c ≈ 1. This result remains valid if two of the three random functions are replaced by a fixedkey ideal cipher in DaviesMeyer mode (i.e., EK(x) ⊕ x for permutation EK). We also give a heuristic, backed by experimental results, suggesting that the security loss is at most four bits for block sizes up to 256 bits. We believe this is the best result to date on the matter of building a collisionresistant compression function from noncompressing functions. It also relates to an open question from Black et al. (Eurocrypt’05), who showed that compression functions that invoke a single noncompressing random function cannot suffice. We also explore the relationship of our problem with that of doubling the output of a hash function and we show how our compression function can be used to double the output length of ideal hashes.
hoc Networks
 Journal
, 2001
"... Abstract — This paper illustrates how networking protocols can inadvertently exacerbate obstacles to providing realtime guarantees for distributed problem solving in wireless mobile and sensor networks. We analyze the effects of control packet timing on providing quality of service guarantees. Inap ..."
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Cited by 14 (0 self)
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Abstract — This paper illustrates how networking protocols can inadvertently exacerbate obstacles to providing realtime guarantees for distributed problem solving in wireless mobile and sensor networks. We analyze the effects of control packet timing on providing quality of service guarantees. Inappropriate timing of control packets gives rise to synchronizations that result in sharp increases and decreases in throughput with small changes in node speed. Such synchronizations can seriously jeopardize network performance with direct effect on realtime guarantees. This paper introduces these synchronizations, analyzes them and suggests ways to modify the control packet timing to overcome them. These analyses include investigating the role of buffering at the network layer and its impact on network throughput. We analyze these effects and evaluate our protocol enhancements through simulation studies. I.
A security design for a general purpose, selforganizing, multihop ad hoc wireless network
 in SASN ’03: Proceedings of the 1st ACM workshop on Security of ad hoc and sensor networks, (ACM
, 2003
"... We present a security design for a general purpose, selforganizing, multihop ad hoc wireless network, based on the IEEE 802.15.4 lowrate wireless personal area network standard. The design employs ellipticcurve cryptography and the AES block cipher to supply message integrity and encryption servi ..."
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Cited by 11 (0 self)
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We present a security design for a general purpose, selforganizing, multihop ad hoc wireless network, based on the IEEE 802.15.4 lowrate wireless personal area network standard. The design employs ellipticcurve cryptography and the AES block cipher to supply message integrity and encryption services, keyestablishment protocols, and a large set of extended security services, while at the same time meeting the low implementation cost, low power, and high flexibility requirements of ad hoc wireless networks.
Hash Functions Based on Block Ciphers and Quaternary Codes
 Advances in Cryptology ASIACRYPT
, 1996
"... . We consider constructions for cryptographic hash functions based on mbit block ciphers. First we present a new attack on the LOKIDBH mode: the attack finds collisions in 2 3m=4 encryptions, which should be compared to 2 m encryptions for a brute force attack. This attack breaks the last remai ..."
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Cited by 10 (2 self)
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. We consider constructions for cryptographic hash functions based on mbit block ciphers. First we present a new attack on the LOKIDBH mode: the attack finds collisions in 2 3m=4 encryptions, which should be compared to 2 m encryptions for a brute force attack. This attack breaks the last remaining subclass in a wide class of efficient hash functions which have been proposed in the literature. We then analyze hash functions based on a collision resistant compression function for which finding a collision requires at least 2 m encryptions, providing a lower bound of the complexity of collisions of the hash function. A new class of constructions is proposed, based on error correcting codes over GF(2 2 ) and a proof of security is given, which relates their security to that of single block hash functions. For example, a compression function is presented which requires about 4 encryptions to hash an mbit block, and for which finding a collision requires at least 2 m encryptions...